Missing translations for WatchList RSS feed for the new add, update, delete for Comment, Attachment, Annotation events

Because XPWATCHLIST uses XPAS (Activity Stream Plugin) since XPWATCHLIST-55 , we need to cover:

• event types for create, edit and delete comment XPAS-19
• event types for create, edit and delete attachment XPAS-20
• event types for create, edit and delete annotation XPAS-21
  introduced for XE 2.6RC1.

The WatchList RSS feed displays for example:
activitystream.event.deleteComment.rss.title
activitystream.event.deleteComment.rss.body
instead of a user friendly message.